1. Field of the Invention
The present invention relates to an image compression apparatus for compressing an image data and a computer-readable recording medium recorded with an image compression program.
2. Description of the Background Art
In recent years, with the development of digital equipment, various compression methods for image data and the like have been proposed. JPEG (Joint Photographic Experts Group) 2000 is known as one of compression methods. JPEG2000 specifies a method for compressing and developing images and is a development of JPEG. JPEG2000 divides an image data into a plurality of tiles and performs a compression process through wavelet transform and quantization for each tile and arithmetic coding for each bit plane. A degree of influence on image quality is calculated for each bit plane and encode data are successively output from the bit planes in order of decreasing degree of influence and coding is so performed that all the bit planes, which has not been encoded yet when a compression ratio designated by a user or the like is reached, becomes data with all “0”s or “1”s. Such rounding of lower bits is described in detail in Japanese Unexamined Patent Publication No. H05-114240.